Abstract: In order to reveal the molecular mechanism underlining the resistant feature of Haloxylon ammodendron, the gene of transcription factor HabHLH74 was cloned from Haloxylon ammodendron and was subsequently expressed in Escherichia coli （E. coli） by using molecular biology technology in this study. The results showed that ① The cDNA sequence of complete coding region of HabHLH74 was successfully amplified using RT-PCR assay, and the length of the coding sequence was 1 218 bp. According to the coding sequence, the physical and chemical properties of its encoding protein were predicted. ② A prokaryotic expression vector of pET28a （+） -HabHLH74 was constructed, and the HabHLH74 protein was expressed successfully in E. coli. The molecular weight of the obtained protein was 43.6 kDa. ③The induced expression condition was optimized by a single factor test. The optimal IPTG concentration, induction temperature and induction time were 0.5 mmol/L, 37 ℃ and 6 h, respectively. ④ Under the optimized induced expression condition, the HabHLH74 protein was expressed in inclusion bodies in E. coli. After decreasing the induction temperature （at 16 ℃ or 25 ℃）, the target protein was still expressed in inclusion form in E. coli.

Key words: Haloxylon ammodendron, HabHLH74 transcription factor, cloning, prokaryotic expression